Abstract: The disclosure is directed to a tissue ablation device comprising an elongate probe, with a tissue ablation member located at the deflectable distal end of the probe, which is configured to access a patient's heart. The elongate probe is attached at its proximal end to a handpiece which is ergonomically designed to fit within the hand of the operator. The handpiece houses an advancement mechanism which is mechanically coupled to the tissue ablation member and can be used to axially translate the tissue ablation member in relation to the elongate probe. An activation mechanism is housed within the advancement mechanism and is coupled to the advancement mechanism in such a manner that the operator can simultaneously activate and advance the tissue removal member with one finger or thumb. The handpiece also houses a deflection actuator which applies tension to a tensile member which deflects the distal end of the probe.